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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Observationally driven Resource Assessment with CoupLEd models (ORACLE)

This project seeks to carry out a multifaceted analysis combining buoy observations, machine learning, turbulence, satellite data and high-resolution modeling. Our analyses will investigate air–sea interaction physics governing the variation of the winds with height and influence of clouds, uncertainty in coupled ocean-wave-atmosphere mesoscale models to capture certain key atmospheric phenomenon observed over the U.S. West Coast, impact of climate change, and the fidelity with which resource characterization models describe the range of observed offshore wind conditions. This project will focus its efforts on characterizing and assessing the atmospheric and oceanographic conditions along the U.S. West Coast.

Wind, Energy↗
NASA NTRS1972

Discontinuities and shock waves in the interplanetary medium and their interaction with the magnetosphere.

The discontinuous structure of the solar wind is described with emphasis on properties related to geomagnetic impulses. Some of the discontinuities are clearly hydromagnetic shocks and tangential discontinuities, and can produce a significant change in the momentum flux at the magnetosphere boundary. Such a change generates an impulse which propagates through the magnetosphere to the earth where it is observed world-wide as an impulse in magnetograms. The propagation process is not reviewed here, but the relation between the initial cause (discontinuity) and the final effect (geomagnetic impulse) is reviewed in detail. The various types of impulses are examined, and are related qualitatively to the various types of discontinuities. The magnitude of an impulse is related to the change in the momentum flux. The propagation time and the rise time depend on the propagation process rather than on the initial state.

Burlaga, L. F.↗
NASA NTRS1973

Lunar electromagnetic scattering. I - Propagation parallel to the diamagnetic cavity axis.

A general analytic solution is obtained for the interaction of the moon and its downstream cavity with a linearly polarized plane electromagnetic wave propagating parallel to the cavity axis. The solution is formulated in terms of a spherical moon model with arbitrary radially dependent electromagnetic parameters and a nonconducting cylindrical downstream cavity. Use is made of a number of approximations that are consistent with the physical nature of the interaction between the moon and the solar wind.

Schwartz, K.↗
NASA NTRS1973

Effects of reaction control system jet simulation on the stability and control characteristics of a 0.015-scale space shuttle orbiter model in the Ames Research Center 3.5-foot hypersonic wind tunnel

An experimental investigation was performed in the Ames Research Center 3.5-Foot Hypersonic Wind Tunnel to obtain detailed effects which interactions between the RCS jet flow field and the local orbiter flow field have on orbiter hypersonic stability and control characteristics. Six-component force data were obtained through an angle-of-attack range of 15 to 35 deg with 0 deg angle of sideslip. The test was conducted with yaw, pitch and roll jet simulation at a free-stream Mach number of 10.3. These data simulate two SSV reentry flight conditions at Mach numbers of 28.3 and 10.3. Fuselage base pressures and pressures on the nonmetric RCS pods were obtained in addition to the basic force measurements. Model 42-0 was used for these tests.

Dziubala, T. J.↗
NASA NTRS1973

Solar flare accelerated isotopes of hydrogen and helium

Measurements of solar flare hydrogen, deuterium, tritium, helium-3, and helium-4 in the energy range approximately 10 to 50 MeV per nucleon obtained with instrumentation on the IMP-4 and IMP-5 satellites are reported and studies based on these results which place several constraints on theories of solar flare particle acceleration are discussed. A brief review of previous work and the difficulties in studying the rare isotopes of hydrogen and helium is also included. Particular emphasis is placed on the fact that the information to be obtained from the solar flare products of high energy interactions is not available through either solar wind observations where both the acceleration mechanism and the coronal source of the nuclear species are different, or optical measurements of solar active regions.

Anglin, J. D.↗
NASA NTRS1975

On the distortion of the Jovian magnetic field R greater than about 40 Jovian radii as deduced from charged particle studies

The relationship between the rotation of Jupiter's magnetic field and time variations in the intensity of nearly 6 to 30 MeV electrons observed by Pioneer 10 in the outer regions of Jupiter's magnetosphere is considered. The 6-30 MeV electron flux showed regular intensity variations with a period of approximately 10 hours. The behavior of this energetic electron flux is found to be most consistent with confinement of particles to a magnetic equatorial plane which is considerably distorted from the shape expected for rigid corotation of the magnetic field with Jupiter. The distortion is likely to arise from stresses resulting from interaction of the magnetosphere with the solar wind and from inertial effects of the magnetospheric plasma.

Mckibben, R. B.↗
NASA NTRS1977

Dynamic pressure studies

The effects on dynamic pressure by errors in viscous interaction of air, navigation filter errors, and wind errors were investigated. Results are summarized in tabular from.

Hall, J. W.↗
NASA NTRS1978

Status of advanced turboprop technology

Research is reviewed in the following areas: turboprop powered transport aircraft; wind tunnel aerodynamic and acoustics tests of model propellers; turboprop maintenance; and wind tunnel tests on airframe-turboprop interactions. Continued development of the technology for advanced turboprop transport was emphasized.

Dugan, J. F.↗
NASA NTRS1980

Secular variations in composition of the solar wind - Evidence and causes

Variations in the composition of the regolith due to irradiation by the solar wind are examined by categorizing the exposure history recorded in each sample. The history can be defined by two parameters: the duration of solar wind exposure (maturity) and a measure of how long the exposure took place (antiquity). Three partially successful methods for determining antiquity are described: the regolith contains small amounts of unsupported, trapped radiogenic noble gases, the most common being Ar-40. Assuming relatively prompt outgassing of the lunar interior, the amount of Ar-40 implanted per unit time should be proportional to the lunar content of K-40, and thus should have decayed exponentially over the lifetime of the moon. Normalization to constant exposure duration is achieved by taking the ratio Ar-40/Ar-36 in trapped gas, Ar-36 being an efficiently trapped solar wind species. The second method involves the interaction between galactic cosmic rays and lunar material producing certain spallogenic nuclides which may be analyzed in terms of a cosmic ray exposure age. The third method deals with the fact that there is a general tendency for depth within a core to be related to time deposition; two variants of this method are presented.

Kerridge, J. F.↗
NASA NTRS1981

Interactive aircraft flight control and aeroelastic stabilization

Several examples are presented in which flutter involving interaction between flight mechanics modes and elastic wind bending occurs for a forward swept wing flight vehicle. These results show the basic mechanism by which the instability occurs and form the basis for attempts to actively control such a vehicle.

Weisshaar, T. A.↗
NASA NTRS1983

The Voyager Mission - Encounters with Saturn

The trajectories of Voyager 1 and Voyager 2 through the Saturnian system were selected in such a way that the observations would be complementary. The Voyager 1 trajectory provided a close encounter with Titan, making possible atmospheric occultations, a search for an intrinsic Titanian magnetic field, and studies of the interaction of Titan with either the solar wind or the Saturnian magnetosphere. The trajectory was also designed to provide an optimum geometry for the transmission of S and X band radio waves from the spacecraft through the rings; in this way, the attenuation and scattering of 3.6- and 13-cm waves by the ring particles could be observed. Besides this, Voyager 1 provided radio and ultraviolet occultation studies of Saturn's atmosphere as well as close approaches to three of the moderate-sized icy satellites (Mimas, Dione, and Rhea) and to a number of minor satellites. The much later arrival of Voyager 2 and the Saturn flyby distance were chosen in such a way as to make possible a gravity-assisted continuation on to Uranus and Neptune.

Stone, E. C.↗
NASA NTRS1984

X-rays from Eta Carinae

X-ray observations of Eta Car obtained with the high-resolution imager and solid-state spectrometer of the Einstein observatory are reported and interpreted in terms of a two-shell model. A soft component with temperature 5 million K is located in the expanding outer shell, and the hard core component with temperature 80 million K is attributed to the interaction of a high-velocity stellar wind from the massive central object with the inner edge of a dust shell. Model calculations based on comparison with optical and IR data permit estimation of the mass of the outer shell (0.004 solar mass), the mass of the dust shell (3 solar mass), and the total shell expansion energy (less than 2 x 10 to the 49th ergs).

Chlebowski, T.↗
NASA NTRS1985

Planetary wave-mean flow interaction in the stratosphere: A comparison between the Northern and Southern Hemispheres

Based on satellite-derived data supplied by the National Meteorological Center (NMC), the dynamical interaction between planetary waves and mean zonal winds in the stratosphere is investigated. Special attention is paid to the differences between the Northern Hemisphere (NH) and the Southern Hemisphere (SH). An analysis is made using Eliassen-Palm (E-P) flux diagnostics for the period from June 1981 to May 1982. In a climatological sense, different seasonal evolutions of large-scale motions between the NH and the SH in the stratosphere are demonstrated. Vertical cross-section analysis is presented to show the day-to-day variation in the mean zonal wind and wave activity, in particular, the following phenomena: (1) the poleward shifting of the westerly jet, and (2) episodes after the shifting of the westerly jet.

Shiotani, M.↗
NASA NTRS1986

The Giotto magnetic-field investigation

The objectives of the Giotto magnetometer experiment are the investigation of the interaction between Comet Halley and the solar wind 0.9 AU from the Sun, to within 500 km of the cometary nucleus, and the study of the interplanetary magnetic field. The instrumentation consists of a triaxial and a separate biaxial system of fluxgate sensors of the ring-core type, the associated analog electronics and a digital processor. The measuring ranges of + or 1 16 up to + or - 65536 nT are digitized by a 12-bit analog-to-digital converter. Memory modes allow the bridging of gaps in telemetry coverage of up to 10 days. Because of the dust hazard near closest approach, a magnetometer boom could not be included in the spacecraft design. The magnetic contamination problem was attacked by the use of two magnetometers and by a magnetic-cleanliness program. In-flight results show that the instrument is working flawlessly, though magnetic-contamination problems remain.

Neubauer, F. M.↗
NASA NTRS1986

The development of shell-like distributions from newborn cometary ions

One-dimensional hybrid computer simulations that are spatially homogeneous are used to investigate the evolution of newborn cometary ions that interact self-consistently with the solar wind. Cometary ions injected at a constant rate are scattered by the growing electromagnetic fluctuations resulting from the associated free energy, and the scattering at relatively low fluctuating field amplitudes leads to shell-like velocity distributions which subtend about 4 pi in solid angle but which have small spread in speed. Shell-like distributions are found to occur when the ion injection rate is relatively slow, when the injected ion mass is relatively light, and when the energy density of the fluctuating magnetic fields exhibits linear growth.

Gary, S. Peter↗
NASA NTRS1987

Low-frequency magnetic field fluctuations in comet P/Halley's magnetosheath - Giotto observations

The interaction region between comets and the solar wind is characterized by large amplitude, low frequency magnetic field fluctuations, both within the upstream region as well as in the magnetosheath. Magnetosheath observations of the magnetic field experiment onboard Giotto indicate values of delta B/B equal to about O(1). Power spectral peaks appear at frequencies of 10mHz with the spectrum exhibiting a power law dependence with an exponent of the order 2. Radial variation of the fluctuation level does not clearly increase with decreasing distance from the cometary nucleus as observed by the magnetometer onboard Vega-1 and as expected from quasi-linear theory. The entrance into the cometary bow shock is furthermore characterized by an order of magnitude increase of the fluctuation level, both on the in- and outbound pass of Giotto.

Glassmeier, K. H.↗